The prior art comprises circuit arrangements designed to detect the presence of errors in a message exchanged between a pair of functional units and which comprise means, disposed in the transmitting sections, adapted to associate a prefixed number of cyclic redundance bits with the bits of each message destined to be transmitted, the said cyclic redundance bits being computed according to a predetermined polynomial arrangement.
The arrangements also comprise means which are disposed in the receiving sections and are designed to detect the presence of errors in the received message through the test of the redundance bits; should the test detect the presence of an error, an alarm criterion is generated. In case of malfunction, this circuit arrangement has the drawback of generating an alarm criterion without being able to give any information about the unit affected by said malfunction; the localization of the fault is therefore difficult.